If you are a gamer, you need to stay on top of the video changes. Go with a 9800 pro and over clock to an xt. With ATIccelator II and some heatsinks as I said before will let you do that. The nice thing is that the price just dropped to 250 bucks. Buy the mac one and you won't need to bother with flashing because it doesn't save that much money anymore. Get it and you will be ready for Doom 3, as long as they decide to make it compatible with the g4. You may need to overclock you cpus though. Check out http://www.bitsandpieces.info for some really good instrucions for that. As I will say in my MDD mod guide, the hard drives are the bottle necks here. Set up a RAID 0 for some serious speed. Hope you can use some of this info.
-Maestro